Yep. The 65 and 55 watt compact fluorescents are 24" long. You get a few inches of space that's gets a little less illumination, just as the front of the tank will if you retrofit the existing light fixture. It's neither good nor bad.
I got into aquatic plant growing by happenstance. 29-gallon tanks are a nice size. It's the largest tank I had room for in my living room. In a perfect house, I would have selected something that would accept better lighting options. Alas, I do have the middle of the room open. Hmmm.